The present invention relates generally to shaft couplings and more particularly to a shaft coupling for transmitting a torque force from one shaft to another.
The problem of how to couple one shaft to another for transmitting a torque force is a long standing one. This has particularly been a problem in the farming community wherein the power take-off of an agricultural tractor frequently needs to be connected and disconnected to utilize one implement and then another. This problem has been solved in the past in one degree or another and one of the most commercially successful of these solutions is a connection of the type disclosed in U.S. Pat. No. 3,747,966 to Wilkes et al. issued in 1973. The commercial success of the coupling of this Wilkes et al. patent has been excellent, but even a quick view of the patent discloses many parts which need to be made and a considerable number of grooves and holes, all of which lead to additional cost and, to some extent, a complicated operation for use.
To operate the coupler of the Wilkes et al. patent referred to above, assuming that the drive train connected thereto is desired to be connected to the power take-off shaft of a tractor, the safety guard of the coupler must be pulled rearwardly to overcome the bias of a spring to allow the coupling elements to permit the coupler to be placed over the power take-off shaft, and while this rearward pulling is accomplished, the operator must also forwardly pull a very heavy drive train having telescoping parts which also add to the drag which must be overcome; and, once the coupler is placed over the power take-off shaft, then the guard can be released so that the coupling elements engage and lock the coupler to the power take-off shaft of the tractor.
If it happens that the splines of the coupler are not aligned with the splines of the power take-off shaft, which happens in a very large percentage of cases, then, in addition to the operation referred to above, a button must be pushed down in the Wilkes et al. coupler and the guard turned while pushing the button down, until a hole in the coupler housing is engaged. Once this has been done, the entire coupling housing may be rotated at the same time that the guard is being pulled back to keep coupler in an unlocked position; and, at the same time that the entire drive chain is being pulled forward in an opposite direction, whereby the coupler can be aligned with the splines of the shaft to complete the coupler operation as described above.
As can be readily appreciated from the above description of the operation of one of the most commercially successful coupling devices on the market today, there is a need for a coupler with a simplified operation for use.